The invention relates to a semiconductor device and a manufacturing method thereof, and particularly, it is suitably applied to a semiconductor device having a super junction structure.
A semiconductor device of a power system adopts a super junction structure as a structure for achieving a lower conductive resistance and a higher junction withstand voltage by arranging pn junctions periodically. To assure a withstand voltage, a semiconductor device of this kind is formed so that a terminal region may surround an element region where power semiconductor elements such as Metal Oxide Semiconductor Field Effective Transistor (MOSFET) are formed. The patent document, for example, Japanese Unexamined Patent Application Publication No. 2014-154596 discloses this kind of semiconductor device.
In the super junction structure, a comparatively deeper groove (deep trench) is formed and through the deep trench, n-type dopant and p-type dopant are injected there; as the result, the pn junctions are arranged periodically. The deep trenches are formed also in the terminal region as well as in the element region. After forming the periodical pn junctions, an insulating film is formed within each deep trench, for example, according to the Chemical Vapor Deposition (CVD).